1. Field of the Invention
The present invention relates to an uninterruptible power supply which is suitable for ensuring that electronic devices such as a computer and a server operate continuously upon failure of a commercial (AC) power supply which serves as a power source for the electronic devices.
2. Description of the Prior Art
With the proliferation of OA (office automation), there is an increasingly higher need for integration of a variety of information (data). To respond to this need, an uninterruptible power supply is provided in order to ensure the operation of an electronic device such as a computer used as an information processing apparatus and a controller in a variety of applications or a peripheral device associated therewith, or such as a server for holding or controlling data in a network system. The uninterruptible power supply is disposed between an associated electronic device and a commercial (AC) power supply, which serves as a power source for the electronic device, such that the uninterruptible power supply powers the electronic device when the commercial power supply fails.
For reference, the uninterruptible power supply is configured to charge its rechargeable battery cells for storing electric energy therein in a normal state, and to retrieve the electric energy from the rechargeable battery cells for powering the electronic device when the commercial power supply fails.
However, since a lead rechargeable battery is typically used as a rechargeable battery cell, conventional uninterruptible power supplies generally become inevitably large and heavy. In addition, the lead rechargeable battery has several problems remained unsolved from an environmental point of view, such as its short lifetime, danger of leaking, and so on, for use as a rechargeable battery cell which is incorporated in an uninterruptible power supply. Also, a conventional uninterruptible power supply operates independently of an associated electronic device, and only powers a power supply unit of the electronic device upon power failure, so that the electronic device cannot detect the state of the rechargeable battery cell in the uninterruptible power supply such as a charge energy, lifetime and so on.